The Morlocks maintained them and bred them like cattle. Only to take them below when they reached maturity.
10 seconds sound clip from the The Time Machine (1960) movie soundboard.
You can hear this line at 01:13:20 in the Blu-ray version of the movie.
Quote context
[...]
- The rest of us decided to take our chances in the sunlight... small as those chances might be.
- By some awful quirk of fate...
- The Morlocks had become the masters and the Eloi their servants.
- Which explained why there were no older people among them.
[...]